Abstract

We report resistance versus magnetic field measurements for a tunnel junctiongrown by molecular-beam epitaxy, that show a large field window of extremely high tunnelingmagnetoresistance(TMR) at low temperature. Scanning the in-plane applied field orientation through 360°, the TMR shows fourfold symmetry, i.e., biaxial anisotropy, aligned with the crystalline axis but not the junction geometrical long axis. The TMR reaches at 4 K, corresponding to an interfacial spin polarization of assuming identical interfaces. These results show that uniaxial anisotropy is not necessary for large TMR, and lay the groundwork for future improvements in TMR in manganite junctions.

Received 24 January 2011Accepted 31 March 2011Published online 20 April 2011

Acknowledgments:

R.W. gratefully acknowledges support by the Cusanuswerk, Bischöfliche Studienförderung. B.A.D. and A.Y.P. acknowledges support by the FVG Regional project SPINOX funded by Legge Regionale Grant No. 26/2005 and Decreto Grant No. 2007/LAVFOR/1461. L.A.-M. thanks the Abdus Salam ICTP (Trieste) for financial support through a STEP fellowship. The TASC Technical group is acknowledged for contributions to the design and construction of the MBE system. This work was funded in part by the Deutsche Forschungsgemeinschaft (Project No. KO 1303/8-1).